MAPT and Cognitive impairment: However, MK usually behaves in the same direction as FA in most of the cases, and its decrease is thought to represent tissue simplification that is likely associated with neuronal shrinkage21,22 and decreased axonal density.23 Several pathological backgrounds of cognitive deficits in iNPH have been proposed, including CSF stagnation and a decrease in the clearance of pathogenic macromolecules like tau and β-amyloid,41 and ischemic damages due to impairment of the periventricular arterioles and venules,42 which are considered as possible to cause decrease in MK.